-- ==
-- error: "a".*consumed

def main n =
  let a = iota (n)
  let b = a
  -- b and a alias each other.
  let (i, j) = (2, 5)
  in (let a[i] = b[j] in a[i])
     + -- Consume a, and thus also b.
       b[j]

-- Error!
